JP4662313B2 - Gas leak detection apparatus and method - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a technique for detecting a gas leak from a main valve of a hydrogen tank.

  A technique for detecting leakage of hydrogen gas, which is a fuel gas, has been developed for a conventional fuel cell system. For example, in Japanese Patent Laid-Open No. 2002-151126, the pressure of a hydrogen tank is detected to detect the amount of hydrogen gas used, while the current amount of hydrogen gas used is estimated from past travel history, and the detected hydrogen gas is detected. Gas leakage is detected based on the estimated amount of hydrogen used and the amount of hydrogen gas used.

  Japanese Patent Application Laid-Open No. 2003-308868 calculates a pressure drop rate based on pressure information from the pressure sensor and an elapsed time after closing the shutoff valve, and the pressure drop rate is smaller than a predetermined threshold value. Discloses an invention for determining that the shut-off valve is in a fault state.

JP 2002-151126 A JP 2003-308868 A

  However, the pressure sensor has a measurable pressure range. Generally, a pressure sensor that can be used in a high pressure range has a wide measurable pressure range, but its measurement accuracy is low. Conversely, a pressure sensor that can be used in a relatively low pressure range has a narrow measurable pressure range, but its measurement accuracy is relatively high.

  Therefore, even if pressure detection is performed without taking into account the situation of the pressure detection means having such characteristics, it is impossible to make a gas leak determination with high accuracy. In this respect, the above-described conventional technology is not considered.

  Therefore, an object of the present invention is to provide a gas leak detection device that can detect a gas leak from a main valve of a hydrogen supply source with high accuracy in accordance with a pressure state of a fuel gas supply path.

  In order to solve the above problems, a gas leak detection device of the present invention is a gas leak detection device of a fuel cell system having a main valve in a fuel gas supply source, and is provided in a fuel gas supply path downstream of the main valve. A plurality of pressure monitoring devices having different pressure ranges for monitoring the pressure of the fuel gas supply path between the shut-off valve, the main valve and the shut-off valve; and a pressure reduction processing apparatus for performing pressure reduction processing in the fuel gas supply path; After the main valve and the shut-off valve are closed, the pressure change in the sealing space of the fuel gas supply path formed between the main valve and the shut-off valve is monitored, and based on the pressure change in the seal space, And a determination device for determining an operation state. In the depressurization process, the fuel gas supply path is depressurized until it enters a pressure range in which pressure monitoring by a plurality of pressure monitoring devices is possible.

  Further, the gas leak detection device of the present invention includes a fuel gas supply source, a main valve that shuts off the fuel gas from the fuel gas supply source, a shutoff valve provided in a fuel gas supply path downstream of the main valve,

  A plurality of pressure monitoring means having different pressure ranges for monitoring the pressure of the fuel gas supply path between the main valve and the shutoff valve, a decompression processing means for decompressing the fuel gas supply path, and a shutoff from the main valve After the valve is closed, the pressure change in the sealing space of the fuel gas supply path formed between the main valve and the shutoff valve is monitored, and the operating state of the main valve is determined based on the pressure change in the sealing space. Determination means for determining. In the depressurization process, the pressure in the fuel gas supply path is reduced to a pressure range in which the pressure monitoring by the plurality of pressure monitoring means is possible.

  Furthermore, the gas leak detection method of the present invention is a gas leak detection method for a fuel cell system provided with a main valve in a fuel gas supply source, the step of closing the main valve while decompressing the downstream side of the fuel gas supply path. And a step of closing the shutoff valve provided in the fuel gas supply passage while reducing the pressure on the downstream side, and the main valve and the shutoff valve are closed between the main valve and the shutoff valve. Monitoring the pressure change in the sealed space of the fuel gas supply path, and determining the operating state of the main valve based on the pressure change in the sealed space. A plurality of pressure sensors having different pressure ranges are provided in the fuel gas supply path. In the step of monitoring the pressure change, one of the pressure sensors is selected for pressure detection according to the pressure in the sealed space. In the step of closing the shut-off valve, the shut-off valve is shut off when the pressure in the sealed space is reduced to a pressure range that allows pressure detection by the pressure sensor that detects the pressure in the sealed space.

  According to the present invention, since the downstream side of the closed main valve is decompressed, a differential pressure is generated between the upstream side and the downstream side of the main valve. If there is a defect in the main valve, such as an abnormal opening / closing of the valve or incomplete sealing, the fuel gas leaks from the main valve due to the differential pressure. Since the pressure-reduced downstream side of the main valve becomes a sealed space by closing the shut-off valve, the pressure in the sealed space should change if fuel gas leaks from the main valve. It is possible to monitor the sealing state of the main valve by monitoring this pressure change.

  In particular, according to the present invention, in the depressurization process, the pressure in the fuel gas supply path is depressurized to a pressure range in which the pressure monitoring device or the pressure sensor can monitor the pressure, so that a pressure condition suitable for pressure detection is recognized. Therefore, the environment can be set according to the characteristics of the pressure detection means. In particular, if the pressure range of the pressure monitoring device or pressure sensor is measurable in a relatively low pressure range, highly accurate pressure detection is possible, and a small amount of gas leakage such as a main valve or shut-off valve can be correctly detected. It can be detected.

  In addition, when the main valve or the shut-off valve is closed, it is preferable that the pressure reducing process is performed on the downstream side, but either the pressure reducing process and the main valve or the shut-off valve closing process may be performed first or simultaneously.

  The “main valve” is also referred to as a (tank) on-off valve or a shut-off valve provided in a fuel gas inlet / outlet portion of a hydrogen supply source (such as a high-pressure tank) or a gas supply passage in the vicinity thereof.

  Here, the “fuel gas supply source” is not limited, and includes various types such as a high-pressure hydrogen tank, a hydrogen tank using a hydrogen storage alloy, a hydrogen supply mechanism using a reformed gas, a liquid hydrogen tank, a liquefied fuel tank, and the like. It is done.

  “Depressurization process” means all processes that can reduce the fuel gas pressure in the supply path. For example, a process that operates a fuel cell and consumes fuel gas, and a purge valve is opened. Then, the process of releasing the pressure, the process of opening the relief valve if provided, and the like.

  The “pressure monitoring device” is a concept that includes a pressure detection unit itself such as a pressure sensor, but also includes a control device that monitors a change in pressure based on information from the pressure detection unit.

  Further, a plurality of pressure monitoring devices having different pressure ranges are provided in the fuel gas supply path, and any one of the pressure monitoring devices performs pressure monitoring according to the reduced pressure in the fuel gas supply path. May be selected. When a pressure monitoring device is provided corresponding to the pressure range, such as for high pressure or low pressure, a pressure monitoring device that can accurately detect the pressure corresponding to the pressure in the gas supply path after decompression. Since it is selected, the leak judgment system can be improved.

  In the present invention, for example, when the pressure change in the sealed space is such that the pressure increases by a predetermined amount or more, it can be determined that the main valve is abnormal. This is because if the fuel gas leaks from the high-pressure fuel gas supply source through the main valve, the pressure in the sealed space should increase.

  Further, for example, when the pressure change amount in the sealed space is such that the pressure decreases by a predetermined amount or more, it is determined that the gas leaks from the fuel gas supply path. For example, it can be determined that the gas leak is caused by a crack such as a hole in the gas pipe. If the main valve is completely closed, if there is a gas leak in the supply passage, the pressure in the supply passage will drop. In addition, even if there is a slight gas leak from the main valve, if there is a gas leak that exceeds the gas inflow from the main valve in the supply path forming the sealed space, the pressure should drop. is there.

  In the present invention, a recovery tank that recovers the fuel gas flowing through the fuel gas supply path and a drive unit that recovers the fuel gas in the recovery tank during the decompression process are provided. According to the above configuration, the fuel gas remaining in the supply path can be recovered and stored in the recovery tank by the driving means, and the fuel gas stored in the recovery tank is supplied to the fuel cell at the next start-up. Is possible.

  Here, the “driving means” refers to a component that forcibly recovers fuel gas, and includes a pump, a compressor, and a turbine.

  Moreover, it is preferable that the shutoff valve and the main valve are closed while the decompression process is continued downstream of the shutoff valve. This is because the shut-off valve and the main valve may constitute, for example, a pilot-type solenoid valve, and the valve having such a configuration can be reliably sealed by performing the shut-off process while reducing the downstream pressure.

1 is a block diagram of a fuel cell system according to a first embodiment. 6 is a flowchart (No. 1) for explaining the control method of the fuel cell system according to the first embodiment. 6 is a flowchart (No. 2) for explaining the control method of the fuel cell system according to the first embodiment. 3 is an operation flowchart at start-up according to the first embodiment. The block of the fuel cell system which concerns on this Embodiment 2. FIG. 7 is a flowchart for explaining a control method of the fuel cell system according to the second embodiment. 10 is an operation flowchart at start-up according to the second embodiment. The functional block diagram in this invention.

  Next, preferred embodiments for carrying out the present invention will be described with reference to the drawings. The following embodiment is merely one embodiment of the present invention, and the present invention is not limited thereto and can be applied.

(Embodiment 1)
In the first embodiment, the gas leak detection device of the present invention is applied to a fuel cell system mounted on a moving body such as an electric vehicle. FIG. 1 shows an overall system diagram of the fuel cell system.

  As shown in FIG. 1, the fuel cell system includes a system for supplying hydrogen gas as a fuel gas to the fuel cell stack 10, a system for supplying air as an oxygen source, and the fuel cell stack 10. And a system for cooling.

The fuel cell stack 10 includes a stack structure in which a plurality of cells including a separator having a flow path of hydrogen gas, air, and cooling water and a MEA (Membrane Electrode Assembly) sandwiched between a pair of separators are stacked. Yes. The MEA has a structure in which a polymer electrolyte membrane is sandwiched between two electrodes, a fuel electrode and an air electrode. The fuel electrode has a fuel electrode catalyst layer provided on the porous support layer, and the air electrode has the air electrode catalyst layer provided on the porous support layer. Since the fuel cell causes reverse reaction of water electrolysis, hydrogen gas as fuel gas is supplied to the fuel electrode side which is a cathode and the air electrode side which is an anode. Oxygen-containing gas (air) is supplied, and a reaction such as equation (1) is generated on the fuel electrode side and a reaction such as equation (2) is generated on the air electrode side to circulate electrons and flow current. It is.
H ₂ → 2H ⁺ + 2e ⁻ (1)
2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)

  A system for supplying hydrogen gas as fuel gas to the fuel cell stack 10 includes a hydrogen tank 11 corresponding to the hydrogen gas supply source of the present invention, a main valve (shutoff valve) SV1, a pressure regulating valve RG, and a fuel cell inlet shutoff valve. The fuel cell outlet cutoff valve SV3, the gas-liquid separator 12 and the gas-liquid separator cutoff valve SV4, the hydrogen pump 13, the circulation path cutoff valve SV6, the recovery tank 15, and the circulation path cutoff valve SV7 are passed through SV2, the fuel cell stack 10. I have. The hydrogen gas is supplied through a hydrogen gas supply path from the main valve SV1 to the fuel cell stack 10, and also includes a pressure regulating valve RG, a shut-off valve SV2, SV3, a gas-liquid separator 12, and a hydrogen pump 13 that partially overlap the supply path. , And also through a circulation path R that circulates through the shutoff valve SV6, the recovery tank 15, and the circulation shutoff valve SV7.

  The hydrogen tank 11 is filled with high-pressure hydrogen gas. Various hydrogen tanks such as a hydrogen tank using a hydrogen storage alloy, a hydrogen supply mechanism using a reformed gas, a liquid hydrogen tank, and a liquefied fuel tank can be applied in addition to a high-pressure hydrogen tank. The supply port of the hydrogen tank 11 is provided with a main valve SV1 according to the present invention. The opening and closing of the main valve SV1 is controlled by a control signal from the control unit 20 to select whether to supply or shut off the hydrogen gas to the supply path. The adjustment amount of the pressure regulating valve RG is determined by the operating state of the compressor 22 on the air electrode side. That is, the pressure of the circulation path R is adjusted by the operation of the compressor 22 and the shutoff valves SV8 and SV9 by the control unit 20. For example, opening the cutoff valve SV8 increases the supply air pressure to the pressure regulating valve RG to increase the supply pressure to the circulation path R, and opening the cutoff valve SV9 decreases the supply air pressure to the pressure regulation valve RG to increase the circulation path R. Reduce the supply pressure to.

  The fuel cell inlet shut-off valve SV2 is closed based on a control signal from the control unit 20 when performing gas leak detection according to the present invention, such as when power generation of the fuel cell is stopped. When the main valve SV1 and the shut-off valve SV2 are closed, the pressure change in the sealed space formed between the main valve SV1 and the shut-off valve SV2 is the pressure sensor p1 or the pressure sensor that forms part of the pressure monitoring device of the present invention. It is detected at p2. The fuel cell outlet cutoff valve SV3 is also closed when the power generation of the fuel cell is stopped.

  The gas-liquid separator 12 removes moisture and other impurities generated by the electrochemical reaction of the fuel cell stack 10 during normal operation from the hydrogen off-gas and discharges them to the outside through the shutoff valve SV4. The hydrogen pump 13 forcibly circulates hydrogen gas in the hydrogen gas circulation path R based on the control signal of the control unit 20. In particular, the hydrogen pump 13 operates so as to forcibly send out hydrogen gas even when power generation is stopped and accumulate it in the recovery tank 15. The purge shut-off valve SV5 is connected to the circulation path R and opened when purging, and is opened when power generation is stopped to reduce the pressure in the circulation path R. The hydrogen off-gas discharged from the purge shut-off valve SV5 is supplied to the diluter 14 and is diluted with the air off-gas. One or more cooperative operations among the fuel cell stack 10, the recovery tank 15, the purge cutoff valve SV5, and the like correspond to pressure reduction processing means for lowering the pressure downstream of the cutoff valve and the main valve.

  The recovery tank 15 has a volume capable of storing the hydrogen staying in the circulation path R so that the hydrogen gas staying in the circulation path R is concentrated and stored in the drive of the hydrogen pump 13 when power generation is stopped. It has become. The shutoff valve SV6 is opened during normal operation, but is shut off by a control signal from the control unit 20 after hydrogen gas is stored in the recovery tank 15 in the power generation stop sequence. Further, it is closed until the hydrogen gas in the recovery tank 15 is consumed at the time of starting. The pressure sensor p3 can detect the pressure in the recovery tank 15 after the shutoff valve SV6 is closed. The circulation shut-off valve SV7 is shut off when power generation is stopped, but is opened when hydrogen gas stored in the recovery tank 15 is supplied to the fuel cell stack 10 at start-up or during normal operation.

  As a system for supplying air to the fuel cell stack 10, an air cleaner 21, a compressor 22, and a humidifier 23 are provided. The air cleaner 21 purifies the outside air and takes it into the fuel electric system. The compressor 22 changes the amount of air and the air pressure supplied to the fuel cell stack 10 by compressing the introduced air based on the control signal of the control unit 20. The humidifier 23 exchanges moisture between the compressed air and the air off-gas to add an appropriate humidity. A part of the air compressed by the compressor 22 is supplied for controlling the pressure regulating valve of the fuel system, and the air pressure in the section between the shutoff valves SV8 and SV9 is applied to the diaphragm of the pressure regulating valve RG. The air off gas discharged from the fuel cell stack 10 is supplied to the diluter 14 to dilute the hydrogen off gas.

  The cooling system of the fuel cell stack 10 includes a radiator 31, a fan 32, and a cooling pump 33, and cooling water is circulated and supplied into the fuel cell stack 10.

  The control unit 20 is a known computer system such as an ECU (Electric Control Unit), and the CPU (Central Processing Unit) (not shown) sequentially executes software programs stored in a ROM (not shown) for carrying out the present invention. The system can be operated as the gas leak detection device of the present invention. That is, according to the procedure (FIGS. 2 to 4) described later, the control unit 20 closes the main valve SV1, depressurizes the fuel gas supply path downstream of the main valve SV1, and is provided downstream of the fuel gas supply path. The fuel cell inlet shut-off valve SV2 is closed to form a sealed space between the main valve and the shut-off valve, the pressure change in the sealed space is monitored, and the original is determined based on the pressure change in the sealed space. It is determined whether or not the valve SV1 is closed.

  The structure of each shut-off valve is not limited. For example, a shut-off valve using a pilot solenoid is used. This is because this type of valve can be expected to increase the fastening force when the present invention is implemented. That is, when the pressure of the hydrogen tank is increased, the fastening force of the valve itself is increased, so that the force when the valve is opened is also increased. In order to reduce the power consumed when the valve is opened, it is preferable to use a pilot type solenoid as in this embodiment. When this type of valve is closed, the current supply to the solenoid is stopped and the valve is closed at a speed determined by the balance between the residual magnetic flux and the spring force. At this time, the strength of the seal of the valve body depends on the biasing force of the spring, but if the pressure downstream of the valve is small, the force is applied to the valve body by the differential pressure before and after the valve, and the reliability of the seal is increased. improves. In this regard, when the shut-off valve (original valve) is closed in this embodiment, the valve closing control signal is supplied after starting the pressure reducing process on the downstream side. For this reason, it is preferable to close the valve while reducing the pressure downstream of the shutoff valve as in this embodiment in order to ensure high sealing performance.

  Next, the operation in the first embodiment will be described with reference to the flowcharts of FIGS. The flowchart is repeatedly executed at appropriate intervals while the power is turned on.

  FIG. 8 shows a functional block diagram realized by the present invention. Each function in FIG. 8 is realized by the control unit 20 controlling based on the flowchart. That is, according to the present invention, a main valve 2 (corresponding to SV1) that cuts off fuel gas from the fuel gas supply source 1 (corresponding to the hydrogen tank 11) and a cutoff provided in the fuel gas supply path 3 downstream of the main valve 2 are provided. A valve 4 (corresponding to SV2 or SV3) and a pressure monitoring means 5 (corresponding to pressure sensors p1, p2 and the control unit 20) for monitoring the pressure of the fuel gas supply path 3 between the main valve 2 and the shutoff valve 4; The decompression processing means 6 (corresponding to the fuel cell stack 10, the recovery tank 15, the purge shutoff valve SV5, etc.), the main valve 2 and the shutoff valve 4 are closed after the fuel gas supply passage 3 is decompressed. Judgment of monitoring the pressure change in the sealed space 7 of the fuel gas supply path 3 formed between the valve 2 and the shutoff valve 4 and determining the operating state of the main valve 2 based on the pressure change in the sealed space 7 Means 8 (corresponding to the control unit 20). In the depressurization process, the pressure in the fuel gas supply path 3 is depressurized to a pressure range in which the pressure monitoring device 5 can monitor the pressure.

The operation according to the configuration of the first embodiment will be specifically described below.
During normal operation (when generating power from the fuel cell), in the fuel cell system, the main valve SV1 is opened and hydrogen gas is supplied to the hydrogen gas supply passage, and the diaphragm of the pressure regulating valve RG is applied by opening and closing the shutoff valves SV8 and SV9. The air pressure is adjusted, and the pressure of the hydrogen gas in the circulation path R is controlled to a desired fuel gas pressure. The fuel cell inlet shutoff valve SV2 and outlet shutoff valve SV3 and shutoff valves SV6 and SV7 are opened, and hydrogen gas is supplied to the fuel electrode of the fuel cell stack 10 while circulating in the circulation path R. In addition, the compressor 22 is appropriately driven, the air having been humidified by the humidifier 23 is added to the air electrode of the fuel cell stack 10, and the air off-gas is discharged to the diluter 14. Hydrogen off-gas containing moisture and the like is supplied to the diluter 14 via the purge shut-off valve SV5 that is opened and closed at an appropriate timing, and is diluted and discharged by the air off-gas.

  The gas leakage determination according to the present invention is normally performed when the fuel cell system is stopped. However, the gas leak determination of the present invention can be performed as long as power generation can be temporarily stopped even during operation.

  As shown in FIG. 2, other power generation processes are executed until the gas leak determination is performed (S1: NO). When it is time to execute the gas leak determination (S1: YES), the control unit 20 continues the power generation that has been continued until then, or further increases or decreases the amount of power generation, so that the fuel system in the fuel cell stack 10 is increased. Hydrogen gas consumption is maintained (S2). This is because a certain amount of hydrogen gas remains in the hydrogen gas supply path and is preferably consumed. By continuing the consumption of the hydrogen gas in the fuel cell stack 10, the fuel gas supply path starts to be decompressed.

  Next, the control unit 20 closes the main valve SV1 of the high-pressure hydrogen tank 11 (S3). This is to stop the power generation by stopping the supply of hydrogen gas from the high-pressure hydrogen tank that is the fuel gas supply source. At this time, since the main valve SV1 is closed while the consumption of hydrogen gas has already been continued, the seal can be made more reliable when the main valve is a pilot solenoid valve or the like. In the present embodiment, at this time, whether or not the main valve SV1 is completely closed is detected by the following procedure.

  First, the hydrogen gas remaining in the circulation path R is collected in the recovery tank 15. For this reason, the controller first closes the circulation shut-off valve SV7 (S4), increases the rotation speed of the hydrogen pump 13 (S6), and sends the hydrogen gas remaining in the circulation path R into the recovery tank 15. . At the same time, the purge shut-off valve SV5 is opened (S5) to reduce the pressure in the circulation path R. Since purge is performed by opening the purge cutoff valve SV5, it is necessary to reduce the concentration of the discharged hydrogen gas. Therefore, the control unit 20 increases the rotational speed of the compressor 22 (S8), and increases the amount of air for diluting the hydrogen off-gas purged by the diluter 14. Due to the recovery of the hydrogen gas to the recovery tank 15 and / or the purging of the hydrogen gas by the purge shut-off valve SV5, the circulation path R is further decompressed.

  The control unit 20 monitors the pressure of the pressure sensor p3 in front of the recovery pump 15 (S9), and determines whether or not the pressure in the recovery tank 15 has reached a predetermined pressure Pc1. Here, the pressure Pc1 is a container protection pressure at which the recovery tank 15 is expected to withstand sufficient hydrogen filling, and is determined by the pressure resistance of the recovery tank 15. For example, it can be set to 1.5 times the breakdown voltage. If the pressure in the recovery tank 15 is lower than the pressure Pc1 (S9: NO), it is determined that the recovery tank 15 is sufficiently pressureable and left to the next determination. In the unlikely event that the pressure of the recovery tank 15 reaches or exceeds this pressure resistance Pc1 (S9: YES), the control unit 20 immediately stops the driving of the hydrogen pump 13 in order to avoid an inconvenient state ( S10) The shutoff valve SV6 at the inlet of the recovery tank is closed to prevent backflow from the recovery tank 15 (S11). Normally, it is considered that the pressure resistance of the recovery tank 15 does not increase.

  With the above processing, the fuel gas path on the downstream side of the main valve SV1 is decompressed. After the pressure reduction process, the pressure fluctuation is measured by the pressure monitoring device of the present invention, that is, the pressure sensors p1 and p2 and the control unit 20 that makes a determination based on the detection signal.

  As shown in FIG. 3, the control unit 20 determines whether or not the in-path pressure has become equal to or lower than a predetermined pressure Pc2 based on the detection signal of the pressure sensor p1 directly below the main valve SV1 (S20). Here, the predetermined pressure Pc2 is set to a pressure at which a sufficient differential pressure is generated between the upstream and downstream of the main valve SV1 to perform the gas leak determination in the present embodiment. If the in-path pressure detected by the pressure sensor p1 is larger than the pressure Pc2 (S20: NO), it is determined that the pressure reduction process should be continued and left to the next determination.

  As described above, the decompression process downstream of the main valve SV1 is achieved by the hydrogen gas consumption process or the purge process by the fuel cell stack 10 and the hydrogen gas recovery process to the recovery tank 15. Even in any one of the processes, the decompression is performed, but the decompression can be performed more quickly by combining a plurality of processes.

  Now, when the pressure in a path | route falls below pressure Pc2 (S20: YES), it transfers to the gas leak determination of this invention. The control unit 20 closes the shut-off valve on the downstream side of the main valve SV1, and measures the change over time in the path pressure. That is, the fuel cell inlet cutoff valve SV2 is closed (S21), the drive of the hydrogen pump 13 is stopped (S22), the purge cutoff valve SV5 is closed (S23), and the fuel cell outlet cutoff valve SV3 is closed (S24). ).

  If the pressure reducing process downstream is continued when the fuel cell inlet shutoff valve SV2 is closed, the seal of the shutoff valve SV2 can be made more complete. That is, when the shutoff valve SV2 is a pilot solenoid valve, the shutoff process is performed while reducing the pressure on the downstream side, so that the seal is assured structurally.

  And it waits until the fixed time t1 passes (S25: NO), and when the time t1 passes (S25: YES), it will be test | inspected whether the fluctuation | variation has arisen in the pressure in a path | route measured with the pressure sensor p1 again. (S26). The reason for waiting for the time t1 is that the pressure fluctuation in the circulation path R after the shutoff valve is closed is taken into account in addition to the response delay of the shutoff valve from the output of the control signal to the actual completion of the shutoff operation. This is because it is necessary to wait until it becomes stable.

  As the next step, the pressure sensor for measuring the pressure fluctuation is switched according to the pressure value reached by the decompression process. Usually, in a pressure sensor, a measurable pressure range is individually determined. A pressure sensor adjusted to measure a relatively high pressure range can measure the pressure in the high pressure range, and a pressure sensor adjusted to measure a relatively low pressure range can measure the low pressure. The pressure in the range can be measured. In general, the pressure accuracy corresponding to a high pressure sensor is lower, and the pressure accuracy corresponding to a low pressure sensor is higher. This is because a pressure sensor corresponding to a low pressure has a smaller measurable pressure range, so that even a smaller pressure change can be identified.

  For example, in the present embodiment, the pressure sensor p1 that measures a relatively high pressure can measure a high pressure but has a relatively low accuracy, whereas the pressure sensor p1 measures a pressure downstream of the pressure regulating valve RG that is a relatively low pressure. The sensor p2 has a small measurable pressure range, but has relatively high accuracy. Although it is preferable to measure with a highly accurate pressure sensor p2 because a slight pressure fluctuation can be detected, the hydrogen gas supply path may not be depressurized as expected. For example, when the seal of the main valve SV1 is incomplete and a control signal for closing the main valve is output, the main valve is not sufficiently closed and a relatively large amount of hydrogen gas has leaked. It is conceivable that the pressure of the hydrogen gas supply path does not drop sufficiently despite the decompression process. In such a case, the pressure sensor p1 for high pressure must be used even if the accuracy is somewhat lowered.

  For this determination, the control unit 20 determines whether or not the pressure of the hydrogen gas supply path is equal to or lower than a predetermined pressure Pc3 using the pressure sensor p1 (S26). Here, the pressure Pc3 is a threshold value for identifying whether it is better to use the low pressure sensor p2 or the high pressure sensor p1. For example, it is set smaller than the maximum pressure that can be identified by the low pressure sensor p2.

  When the pressure sensor p2 for low pressure is to be used (S26: YES), the control unit 20 monitors the pressure fluctuation based on the detection signal of the pressure sensor p2 for a certain time (S30). For example, the pressure detected by the pressure sensor p2 at a certain time is stored, and after waiting for a certain time, the pressure detected by the pressure sensor p2 is stored again. Then, the amount of change is obtained by obtaining the difference between the two pressures. Or you may make it measure more than 3 times, calculate the average, and obtain | require more reliable pressure fluctuation. As a result, when the pressure has increased and the amount of change is equal to or greater than the predetermined pressure difference Pc4 (S31: YES), since the pressure has increased, the valve closing abnormality of the main valve SV1 can be sufficiently estimated. A valve seal SV1 abnormality handling process is performed (S32). This process can be considered in various ways depending on the configuration of the fuel cell system. For example, a process of stopping the fuel cell or lighting a warning lamp in the interior of the electric vehicle to warn the user of the necessity of service. Can be considered. The pressure difference Pc4 is set to a threshold value that can sufficiently identify the pressure increase due to the gas leakage from the main valve SV1 at low pressure.

  Further, when the pressure is decreasing and the amount of change is equal to or greater than the predetermined pressure difference Pc6 (S31: NO, S33: YES), the pressure that should not drop is decreasing, so it leaks somewhere in the path. May have occurred. Therefore, a hydrogen leak handling process (S34) is performed. In addition to the lighting of a warning lamp for stopping the fuel cell or warning the necessity of service to the user, the processing includes the subsequent pressure of the hydrogen gas supply path and the circulation path R in order to minimize gas leakage. Measures such as lowering the upper limit can be considered. It is also possible to prohibit the operation of the fuel cell system until repair is completed. Note that the predetermined pressure difference Pc6 is set to a threshold value that can identify a pressure drop amount at which hydrogen leakage is sufficiently estimated under a low pressure.

  On the other hand, when it is determined that the high-pressure sensor p1 should be used (S26: NO), the controller 20 similarly monitors the pressure fluctuation detected by the pressure sensor p1 for a certain period of time (S40). The way of monitoring is the same as that of the pressure sensor p2. As a result, when the pressure has increased and the amount of change is equal to or greater than the predetermined pressure difference Pc5 (S41: YES), since the pressure has increased, the valve closing abnormality of the main valve SV1 can be sufficiently estimated. A valve seal SV1 abnormality handling process is performed (S42). This process can be considered as in step S32. The pressure difference Pc5 is set to a threshold value that can sufficiently identify the pressure increase due to gas leakage from the main valve SV1 at high pressure.

  If the pressure is decreasing and the amount of change is equal to or greater than the predetermined pressure difference Pc7 (S41: NO, S43: YES), the pressure that should not drop is decreasing, so there is a defect somewhere in the path. May have occurred. Therefore, a hydrogen leak handling process (S44) is performed. This process can be considered as in step S34. Note that the predetermined pressure difference Pc7 is a threshold value that can identify a pressure drop amount at which hydrogen leakage is sufficiently estimated under high pressure.

  If none of the above applies (S33: NO, S43: NO), the process is terminated assuming that there is no valve closing abnormality of the main valve SV1 or gas leakage in the hydrogen gas supply path.

  Although the gas leak determination of this embodiment is complete | finished above, when starting the next electric vehicle (fuel cell system), the hydrogen gas accommodated in the collection tank 15 must be used preferentially. Therefore, hydrogen gas is used in the process as shown in FIG. First, when the activation is instructed (S50: YES), the control unit 20 opens the circulation cutoff valve SV7, the recovery tank cutoff valve SV6, the fuel cell inlet cutoff valve SV2, and the fuel cell outlet cutoff valve SV3 that have been closed until then. Open (S52). Through the above processing, the hydrogen gas stored from the outlet of the recovery tank 15 is supplied to the hydrogen gas supply path, and power generation is started with the hydrogen gas.

  As long as hydrogen gas remains in the recovery tank 15 (S52: NO), the outlet pressure (recovery tank pressure) p3 of the hydrogen pump 13 does not decrease. Therefore, when the hydrogen pump outlet pressure p3 is higher than the predetermined pressure Pc9 (S52: NO), power generation using the hydrogen gas in the recovery tank 15 is executed, and the hydrogen pump outlet pressure p3 becomes Pc9 or less. In this case (S52: YES), a control signal that opens the main valve SV1 of the high-pressure tank 11 for the first time is supplied (S53). At the same time, a control signal for driving the hydrogen pump 13 is also output. The threshold value Pc5 for determining the pressure in the recovery tank 15 is set to a threshold value that can identify whether the hydrogen gas in the recovery tank 15 remains or has been supplied.

  According to the first embodiment described above, since the gas leakage of the main valve can be appropriately determined, it is possible to cope with the hydrogen tank 11 having a high pressure.

  Further, according to the first embodiment, even if a large amount of hydrogen gas stays in the hydrogen gas supply path or the circulation path R by increasing the pressure of the hydrogen tank 11, the hydrogen gas in the path is stopped when the operation is stopped. Since the fuel is fed into the recovery tank 15, the inside of the circulation path R when the operation is stopped can be kept in a safe state with very little hydrogen gas.

  In particular, according to the present embodiment, since the pressure sensor that monitors the pressure fluctuation is selected according to the pressure in the hydrogen gas supply path after the decompression process, a pressure sensor with higher accuracy is selected according to the pressure at that time, Hydrogen gas leakage from the main valve SV1 can be detected with high accuracy and accuracy.

  Further, since the shutoff valves SV2, SV3, SV6, and SV7 are closed during the decompression process, for example, a pilot-type solenoid valve or a valve having a similar structure is used as the shutoff valve to enhance the sealing effect. be able to. This is because these valves can improve the sealing performance by performing a shut-off process while reducing the pressure on the wake side.

  Furthermore, if the pressure change amount downstream of the sealed main valve SV1 is a pressure equal to or higher than a predetermined value, it is determined that the main valve is defective and if the pressure is lower than the predetermined value, it is determined that the hydrogen gas supply path is defective. A plurality of gas leakage modes can be detected.

  Moreover, since hydrogen gas can be first supplied from the collection tank 15 at the time of starting, it is economical.

(Embodiment 2)
The second embodiment of the present invention relates to a structure in which the recovery tank of the first embodiment is provided in the main valve SV1. FIG. 5 is an overall system diagram of the fuel cell system according to the second embodiment.

  As shown in FIG. 5, the fuel cell system according to the second embodiment has substantially the same structure as the system according to the first embodiment, but a recovery tank 15 is provided in the vicinity of the main valve SV1.

  That is, a hydrogen gas supply path to the recovery tank 15 is connected downstream of the main valve SV1, and a circulation path including the hydrogen pump 16, the cutoff valve SV10, the pressure sensor p4, the recovery tank 15, and the cutoff valve SV11 is provided. ing. In the circulation path R, a check valve RV is provided in place of the recovery tank 15 and the circulation cutoff valve SV7. The junction of the circulation path R to the hydrogen gas supply path is downstream of the pressure regulating valve RG. Other configurations are the same as those of the first embodiment shown in FIG.

  Next, the operation in the second embodiment will be described with reference to the flowcharts of FIGS. The flowchart is repeatedly executed at appropriate intervals while the power is turned on.

  The processing during normal operation (when generating fuel cells) is as described above. First, as shown in FIG. 6, other power generation processes are executed until the gas leak determination is performed (S61: NO). When it is time to perform a gas leak determination (S61: YES), the control unit 20 closes the main valve SV1 of the high-pressure hydrogen tank 11 while maintaining the consumption of hydrogen gas in the fuel system (S62) as in the first embodiment. (S63).

  In the present embodiment, the hydrogen gas in the circulation path R is depressurized by purging from the fuel cell stack 10 and the purge control valve SV5. The controller 20 closes the shut-off valve SV6 and closes the circulation path R (S64), opens the purge shut-off valve SV5 (S65), and increases the rotational speed of the compressor 22 (S68).

  On the other hand, the control unit 20 drives the hydrogen pump 16 and opens the shut-off valve SV10 in order to store the hydrogen gas remaining in the hydrogen gas supply path upstream of the pressure regulating valve RG in the recovery tank 15 (S66). Next, as in the first embodiment, the control unit 20 monitors the pressure of the pressure sensor p4 located in front of the recovery pump 15 (S69), and whether or not the pressure in the recovery tank 15 has reached a predetermined pressure Pc1. Determine. If the pressure in the recovery tank 15 is lower than this pressure Pc1 (S69: NO), it is determined that the recovery tank 15 can sufficiently withstand the pressure, and the next determination is made. When the pressure exceeds the pressure resistance Pc1 (S69: YES), the driving of the hydrogen pump 16 is immediately stopped (S70), and the shutoff valve SV10 at the inlet of the recovery tank is closed in order to prevent backflow from the recovery tank 15 ( S71).

  With the above processing, the fuel gas path on the downstream side of the main valve SV1 is decompressed. After the decompression process, the pressure fluctuation is measured in substantially the same manner as in the first embodiment (see FIG. 3). That is, the control unit 20 shuts off a shut-off valve for shutting off the sealed space related to the gas leak determination while continuing the decompression process, and monitors a pressure change in the sealed space.

  When the next electric vehicle (fuel cell system) is started, the hydrogen gas stored in the recovery tank 15 is preferentially used by the process shown in FIG. First, when the activation is instructed (S100: YES), the control unit 20 opens the shut-off valves SV10 and SV11 before and after the recovery tank 15 that have been closed until then, and at the same time the shut-off valve SV6 of the circulation path R, the fuel cell. The inlet cutoff valve SV2 and the fuel cell outlet cutoff valve SV3 are opened (S101). Through the above processing, the hydrogen gas stored from the outlet of the recovery tank 15 is supplied to the hydrogen gas supply path, is regulated by the pressure regulating valve RG, is supplied to the fuel cell stack 10, and power generation is started.

  As long as hydrogen gas remains in the recovery tank 15 (S102: NO), the outlet pressure (recovery tank pressure) p4 of the hydrogen pump 16 does not decrease. Therefore, when the hydrogen pump outlet pressure p4 is higher than the predetermined pressure Pc9 (S102: NO), power generation using the hydrogen gas in the recovery tank 15 is executed, and the hydrogen pump outlet pressure p4 becomes Pc9 or less. In this case (S102: YES), a control signal that opens the main valve SV1 of the high-pressure tank 11 for the first time is supplied (S103). At the same time, a control signal for driving the hydrogen pump 13 in the circulation path R is also output.

  According to the second embodiment described above, the present invention can be implemented even when a recovery tank is provided near the main valve other than the circulation path R, and the same effects as those of the first embodiment can be achieved.

(Other embodiments)
The present invention is not limited to the above embodiments and can be used with various modifications. For example, the position where the recovery tank is provided is not limited to the above embodiments, and various design changes can be made. Of course, it is also possible to apply the gas leakage determination processing of the present invention to a system without a recovery tank.

  The circulation path R is not an essential configuration, and the present invention can also be applied to a fuel cell system that does not circulate fuel gas.

  Further, in the above embodiment, the presence or absence of gas leakage with respect to the main valve SV1 is detected, but it is possible to determine the valve opening or sealing reliability for the downstream shut-off valves SV2, SV3, SV6 in the same manner. It is. That is, a pressure sensor is provided downstream of the downstream shut-off valves SV2, SV3, SV6, and a sealing space is formed in a path between the shut-off valve and one shut-off valve on the downstream side. By detecting the pressure fluctuation with a pressure sensor or the like, it is possible to detect a gas leak due to an abnormality in the opening of the upstream shut-off valve, a seal abnormality, or the like. If the pressure fluctuation in the sealed space has a tendency to increase in pressure, an abnormality of the upstream shut-off valve can be estimated, and if it has a tendency to decrease in pressure, gas leakage in the route section can be estimated.

  As described above, according to the present invention, the downstream side of the closed main valve is decompressed to form a sealed space, and the pressure change is monitored, so that the closed state of the main valve can be reliably detected. In particular, since the pressure reduction process is controlled so that the pressure monitoring is performed with high accuracy, it is possible to detect gas leakage with high accuracy.

  Therefore, the present invention is applicable to general fuel cell systems that require gas leak detection. Even if the fuel cell system is mounted on a ground mobile object such as a vehicle, a marine mobile object such as a ship, an underwater mobile object such as a submarine, or an aerial mobile object such as an aircraft, Even if it is installed as real estate, it can still be used.

Claims (8)

A gas leak detection device for a fuel cell system comprising a main valve in a fuel gas supply source,
A shutoff valve provided in a fuel gas supply path downstream of the main valve;
Wherein for monitoring the pressure of the fuel gas supply passage, a plurality of pressure monitoring devices having different pressure ranges between said main valve and said shut-off valve,
A decompression processor for decompressing process the fuel gas supply passage,
Pressure change of the sealing space by monitoring the pressure change in the sealing space of the fuel gas supply passage and the main valve and the shut-off valve is formed between the main valve and the shut-off valve after being closed and a determining device the operating state of the main valve on the basis of,
The decompression processing, the plurality of said fuel gas supply passage to enter the pressure range that can be pressure monitored is reduced in pressure monitoring apparatus, the gas leakage detection system according to claim.   The gas leak detection device according to claim 1, wherein the pressure monitoring device at any position is selected to monitor the pressure in accordance with the reduced pressure of the fuel gas supply path.   The gas leak detection device according to claim 1, wherein when the pressure change in the sealed space is such that the pressure increases by a predetermined amount or more, it is determined that the main valve is abnormal.   The gas leak detection device according to claim 1, wherein when the pressure change amount in the sealed space is such that the pressure drops by a predetermined amount or more, it is determined that the gas leaks from the fuel gas supply path. Furthermore, a recovery tank that recovers the fuel gas flowing through the fuel gas supply path;
The gas leak detection device according to claim 1, further comprising a drive unit that recovers the fuel gas to the recovery tank during the decompression process.   The gas leak detection device according to claim 1, wherein the shutoff valve and the main valve are closed during pressure reduction downstream. A fuel gas supply source;
A main valve to shut off the fuel gas from the fuel gas supply source,
A shutoff valve provided in a fuel gas supply path downstream of the main valve;
And the fuel gas supply passage for monitoring the pressure of a plurality of different pressure monitoring means having a pressure range between said main valve and said shut-off valve,
A decompression processing means for vacuum processing said fuel gas supply path,
Monitoring the pressure change in the sealing space of the fuel gas supply passage and the main valve and the shut-off valve is formed between the main valve and the shut-off valve after being closed the pressure of those said sealing space based on the change and a determination means for determining an operating state of said main valve,
The decompression processing, the plurality of the pressure of the fuel gas supply path to the pressure range that can pressure monitoring is reduced in pressure monitoring means, the gas leakage detection system according to claim. A method for detecting a gas leak in a fuel cell system including a main valve in a fuel gas supply source,
A step of closing process the main valve while reducing the pressure processing downstream of the fuel gas supply passage,
A step of closing process the shutoff valve provided on the downstream side to the fuel gas supply passage while reducing the pressure treatment,
After said main valve and said shut-off valve is closed process, the steps of monitoring the pressure change in the sealing space of the fuel gas supply passage formed between the main valve and the shut-off valve,
And a step of determining the operating state of the source valve based on a pressure change in the sealed space,
A plurality of pressure sensors having different pressure ranges are provided in the fuel gas supply path,
In the step of monitoring the pressure change, according to the pressure in the sealed space, any one of the pressure sensors is selected for pressure detection,
In the step of closing process the shut-off valve, the shut-off valve is shut off when the pressure of the sealed space to a pressure range capable of pressure detection of the pressure sensor for detecting the pressure in the sealing space is depressurized Gas leak detection method.

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